Re: [PATCH v3 2/6] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
Hi Peter,
On 2016/04/20 at 21:49, Xunlei Pang wrote:
> On 2016/04/20 at 21:19, Peter Zijlstra wrote:
>> On Thu, Apr 14, 2016 at 07:37:03PM +0800, Xunlei Pang wrote:
>>> + /* Updated under pi_lock and rtmutex lock */
>>> struct rb_node *pi_waiters_leftmost;
>>> + struct rb_node *pi_waiters_leftmost_copy;
>>> struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
>>> {
>>> + if (!task->pi_waiters_leftmost_copy)
>>> return NULL;
>>>
>>> + return rb_entry(task->pi_waiters_leftmost_copy,
>>> + struct rt_mutex_waiter, pi_tree_entry)->task;
>>> }
>> why ?! Why not keep a regular task_struct pointer and avoid this stuff?
> I meant to make it semantically consistent, but I can change it since you
> think task_struct is better.
What do you think this version of PATCH1 and PATCH2?
If you are fine with it, I can sent it out as v4 separately, then we can focus
on the issue in PATCH5.
Thanks!
>
> Regards,
> Xunlei
Re: [PATCH v3 2/6] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
Hi Peter,
On 2016/04/20 at 21:49, Xunlei Pang wrote:
> On 2016/04/20 at 21:19, Peter Zijlstra wrote:
>> On Thu, Apr 14, 2016 at 07:37:03PM +0800, Xunlei Pang wrote:
>>> + /* Updated under pi_lock and rtmutex lock */
>>> struct rb_node *pi_waiters_leftmost;
>>> + struct rb_node *pi_waiters_leftmost_copy;
>>> struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
>>> {
>>> + if (!task->pi_waiters_leftmost_copy)
>>> return NULL;
>>>
>>> + return rb_entry(task->pi_waiters_leftmost_copy,
>>> + struct rt_mutex_waiter, pi_tree_entry)->task;
>>> }
>> why ?! Why not keep a regular task_struct pointer and avoid this stuff?
> I meant to make it semantically consistent, but I can change it since you
> think task_struct is better.
What do you think this version of PATCH1 and PATCH2?
If you are fine with it, I can sent it out as v4 separately, then we can focus
on the issue in PATCH5.
Thanks!
>
> Regards,
> Xunlei
Re: [PATCH v3 2/6] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
On 2016/04/20 at 21:19, Peter Zijlstra wrote:
> On Thu, Apr 14, 2016 at 07:37:03PM +0800, Xunlei Pang wrote:
>> +/* Updated under pi_lock and rtmutex lock */
>> struct rb_node *pi_waiters_leftmost;
>> +struct rb_node *pi_waiters_leftmost_copy;
>> struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
>> {
>> +if (!task->pi_waiters_leftmost_copy)
>> return NULL;
>>
>> +return rb_entry(task->pi_waiters_leftmost_copy,
>> +struct rt_mutex_waiter, pi_tree_entry)->task;
>> }
> why ?! Why not keep a regular task_struct pointer and avoid this stuff?
I meant to make it semantically consistent, but I can change it since you think
task_struct is better.
Regards,
Xunlei
Re: [PATCH v3 2/6] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
On 2016/04/20 at 21:19, Peter Zijlstra wrote:
> On Thu, Apr 14, 2016 at 07:37:03PM +0800, Xunlei Pang wrote:
>> +/* Updated under pi_lock and rtmutex lock */
>> struct rb_node *pi_waiters_leftmost;
>> +struct rb_node *pi_waiters_leftmost_copy;
>> struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
>> {
>> +if (!task->pi_waiters_leftmost_copy)
>> return NULL;
>>
>> +return rb_entry(task->pi_waiters_leftmost_copy,
>> +struct rt_mutex_waiter, pi_tree_entry)->task;
>> }
> why ?! Why not keep a regular task_struct pointer and avoid this stuff?
I meant to make it semantically consistent, but I can change it since you think
task_struct is better.
Regards,
Xunlei
Re: [PATCH v3 2/6] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
On Thu, Apr 14, 2016 at 07:37:03PM +0800, Xunlei Pang wrote:
> + /* Updated under pi_lock and rtmutex lock */
> struct rb_node *pi_waiters_leftmost;
> + struct rb_node *pi_waiters_leftmost_copy;
> struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
> {
> + if (!task->pi_waiters_leftmost_copy)
> return NULL;
>
> + return rb_entry(task->pi_waiters_leftmost_copy,
> + struct rt_mutex_waiter, pi_tree_entry)->task;
> }
why ?! Why not keep a regular task_struct pointer and avoid this stuff?
Re: [PATCH v3 2/6] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
On Thu, Apr 14, 2016 at 07:37:03PM +0800, Xunlei Pang wrote:
> + /* Updated under pi_lock and rtmutex lock */
> struct rb_node *pi_waiters_leftmost;
> + struct rb_node *pi_waiters_leftmost_copy;
> struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
> {
> + if (!task->pi_waiters_leftmost_copy)
> return NULL;
>
> + return rb_entry(task->pi_waiters_leftmost_copy,
> + struct rt_mutex_waiter, pi_tree_entry)->task;
> }
why ?! Why not keep a regular task_struct pointer and avoid this stuff?
